Ligands

Question 1

Define Ligands.

Answer 1

-Neutral Molecule / ions
-Attached to Central Metal ions

 The neutral molecules or ions (usually anions) which are attached with the central ion in
complex compounds are called ligands or co-ordinating groups.
 The ligands are arranged round the central metal ion inside the first sphere of attraction in
preferred geometries which are : linear, equilateral triangular, tetrahedral, square planar,
trigonal bipyramidal, square pyramidal and octahedral.

Question 2

What are two character of Ligands?

Answer 2

• Lewis Acids = electron acceptors
• Lewis base = electron donors

Question 3

Differentiate Ligands on the bases of number.

Answer 3

NO. OF LIGANDS
1. MONODENTATE
2. BIDENTATE
3. TRIDENTATE
4. TETRADENTATE
5. PENTADENTATE
6. HEXADENTATE
POLYDENTATE

Question 4

What are Monodentate Ligands?

Answer 4

• Ligands with only one electron pair donor

Question 5

What are Polydentate Ligands?

Answer 5

Ligands with two or more donor atoms.

Question 6

What are different types of Polydentate Ligands?

Answer 6

BIDENTATE
TRIDENTATE
TETRADENTATE
PENTADENTATE
HEXADENTATE

Question 7

What are different types of Bidentate Ligands?

Answer 7

-Anionic Bidentate
- Neutral Bidentate

Question 8

What are different types of Anionic Bidentate Ligands?

Answer 8

-Oxalato ; didentate dibasic ligand
- Glycinato ; didentate monobasic ligand

Question 9

Give an example of Neutral Bidentate Ligand

Answer 9

o-phenanthroline (2 N- donor atoms)

Question 10

What are the two anionic Tridentate ligands?

Answer 10

• Anion of Aspartic acid
  -Anion of diaminopropanoic acid

Question 11

What is the ligand of Anionic Aspartic Acid?\
Where does coordination occur?

Answer 11

-OOC-Ch2- CH(nH2)-COO-
Tridentate diabasic Ligand

Coordination occur with N (neutral) and two negative charged O (acid donor)

Question 12

What is the ligand in Anionic diamopropanoic acid? Where does Coordination occur?

Answer 12

H2C (Nh2)-CH(Nh2)-COO- (Tridentate Monobasic Ligand)

Coordination occur with 3 N-atoms (neutral donor) to formation with one -ve charged O atom (acidic donor)

Question 13

Give an example of neutral tridentate ligand. where does Coordination occur?

Answer 13

triammino propane
CH2(NH2)-CH(NH2)

Question 14

what is coordination number?

Answer 14

 The number of ligands which are directly attached with the central metal atom/ion is known as the coordination number of that metal atom/ion.
 Light transition metal atoms prefer to attain 4 and 6 coordination numbers while the heavier
transition metal atoms exhibit coordination numbers greater than 6. A metal atom may exhibit
more than one coordination number in different complexes.